It is a continuing goal in the metalcutting industry to provide metalcutting inserts with sharp cutting edges that stay sharp longer, even when machining nonferrous and abrasive materials. To this end, it has been know to incorporate polycrystalline diamond materials and polycrystalline cubic boron nitride (CBN) materials on a carbide substrate to provide an improved cutting edge. One example of such an insert is the polycrystalline diamond positive insert provided by Kennametal Inc., the assignee of the present invention. Considering the TPG style positive insert (a triangularly shaped metalcutting insert) as an exemplar, the polycrystalline material is bonded onto one edge thereof so as to maintain the integrity of the original dimensions of the insert. This insert, in turn, can then be properly mounted in a toolholder.
Heretofore, in such inserts incorporating advanced metalcutting materials, all chipbreaking capabilities had to be provided to the insert and toolholder through the use of a mechanical device. Such mechanical devices typically include a metal ramp or clamp element which are used at least in part to fixedly secure the cutting insert onto a toolholder. Problems with accurate placement of the mechanical devices could tend to limit or to diminish the effectiveness of these types of chipbreaking devices.
It is an object of the present invention to provide an improved metalcutting insert which utilizes a polycrystalline diamond material or a polycrystalline cubic boron nitride (CBN) material in combination with a metalcutting insert substrate, which substrate incorporates therein integral chipbreaking features.
It is yet another object of this invention to provide an improved cutting tool with a sharp cutting edge that stays sharp longer for use in metalcutting operations.